Avalanche Burial, Hypercapnic Respiratory Failure, Hypoxic Respiratory Failure, Snow Physical Properties
Conditions
Brief summary
Sufficient oxygenation is critical for completely buried avalanche victims to avoid life-threatening consequences during hypoxic exposure. Snow contains a remarkable capacity to maintain air availability; it was suspected that the snow physical properties affect the development of hypoxia and hypercapnia. The aim of this study was to evaluate the influence of different snow physical properties on the development of hypoxia and hypercapnia in subjects breathing into an artificial air pocket in snow. Twelve male healthy subjects breathed through an airtight face-mask and 40cm tube into an artificial air pocket of 4L. Every subject performed three tests on different days with varying snow characteristics. Symptoms, gas and cardiovascular parameters were monitored up to 30min. Tests were interrupted at SpO2 \<75% (primary endpoint); or due to subjective symptoms like dyspnea, dizziness, and headache (i.e. related to hypercapnia). Snow density was assessed via standard methods and micro-computed tomography (CT) analysis, and permeability and penetration with the snow micro-penetrometer (SMP).
Interventions
OTHERBreathing in snow
Breathing in snow with different physical properties
Sponsors
Medical University Innsbruck
Institute of Mountain Emergency Medicine
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
DOUBLE (Subject, Investigator)
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* Healthy volunteers with an age above 18yr-old, physically active. * Volunteers have been informed and have signed consent.
Exclusion criteria
* Lack of consent. * Chronic previous illness of the respiratory tract or of the cardiovascular system. * Acute disease at or immediately prior to the test (eg, flu-like infection, fever of unknown origin). * Eurac employees.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| SpO2 (%) | Changes from baseline (measurement at 0min) -> snow-breathing phase (5min, 15min, and timepoint immediately before interruption of snow-breathing phase [max 30min]) -> 2.5min and 5min after snow-breathing phase | Continuous monitoring |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| EtCO2 (mmHg) | Changes from baseline (measurement at 0min) -> snow-breathing phase (5min, 15min, and timepoint immediately before interruption of snow-breathing phase [max 30min]) -> 2.5min and 5min after snow-breathing phase | Continuous monitoring |
| Cause of interruption | Timepoint immediately before interruption of snow-breathing phase (max 30min) | SpO2 \<75% or subjectives symptoms due to hypercapnia (like dyspnea, dizziness, and headache) |
| VE (L/min) | Changes from baseline (measurement at 0min) -> snow-breathing phase (5min, 15min, and timepoint immediately before interruption of snow-breathing phase [max 30min]) -> 2.5min and 5min after snow-breathing phase | Continuous monitoring |
| rSO2 (%) | Changes from baseline (measurement at 0min) -> snow-breathing phase (5min, 15min, and timepoint immediately before interruption of snow-breathing phase [max 30min]) -> 2.5min and 5min after snow-breathing phase | Continuous monitoring |
Countries
Italy
Outcome results
None listed